Hollow metal beam



Se'pt.'8,-1925. v 1,552,474

- C. DORNIER HOLLOW METAL BEAM Filed Nov. 20, 1920 2 Sheets-Sheet l Sept. 8, 1925. 1,552,474

C. DORNIER HOLLOW METAL BEAM Filed Nov. 20, 1920 2 Sheets-Sheet 2 Patented Sept. 8, 1925.

UNITED STATES:

CLAUDE DORNIER, or rmnnnronsnarnn, GERMANY.

HOLLOW METAL BEAM.

Application filed November 20, 1920. Serial No. 425,585.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.) I

To all whom it may concern:

, Be it known that I, CLAUDE DoRNIER, a

; citizen of the German Empire, residing at Friedrichshafen-on the-Bodensee, Germany, have invented certain new and useful Improvements in Hollow Metal Beams (for i which I have filed applications in Germany July 2, 1917, Patent'No. 372.639, and'Oct. 22, 1917), of which the following is a specification.

My invention refers to girders and other construction members of a similar nature and more especially to hollow beams or girders of flying machine supporting surfaces.

Obviously hollow beams of the kind aforesaid are required to combine greatest strength with extreme light weight and on the other ha (1 greatest ease of manufacture, even on a 1 rge scale, with sufficient exactitude of section. Such beams are further re-- quired not to undergo even at considerable variations of temperature any reduction,

- due to buckling or bulging, of the good fitting together with other members of construction such as the ribs of supporting surfaces and the like.

The beam or girder according to the present invention answers all the. above requirements owing to its having the form of a box shaped hollow beam made of suitable material and presenting an especially favourable section at its ends.

In accordance with the aforesaid the invention substantially consists in a hollow metal beam formedof a seamless thin walled tube of quadrangular section. It is of no avail, as far as the present invention is con cerned, what means and methods have been employed for transforming the originally circular section of the tube into a quadrangular one. Onthe other hand it is important that the final section does not present merely solid and continuous even walls, for in such a case owing to the small thick ness of the walls bulging and buckling of the-side faces could not be avoided. Therefore according to the present invention at least two sides facing each other are stepped inwards in close proximity to the edges. The formation of steps is preferably carried through at the two broader faces in order to prevent these latter from suffering any injurious bulging or buckling even at greater variations of temperature. In order to reduce as far as possible the weight of the hollow beam, the faces stiffened by means of the steps may be pro 'vided with openings in a well known manner.

In certain cases it may prove advanta-. geous to brace also the narrow faces, and

in that case the beam is resting only with the portions adjoining its edges within the.

guide openings of other construction members such as the ribs which surround it. In this case it may be adapted with the greatest-accuracy to the diameter of thesaid guide openings in height as well as in breadth. The edges of the openings in the faces forming a trellis work are preferably bent inwards so as to prevent the said edges from extending into the open space of the guide faces.

By first converting the seamless tube into a quadrangular one of. the desired cross section andonly thereafter forming the steps and openings in the single faces, a hollow girderof greatestpossible exactness is obtained inasmuch as a buckling of the faces, which latter had at first been made even, is out of the question and the stamping out of single portions thereof can .be carried out-- 1" may however also utilize the novel feature of providing at least two side walls of the beam with steps, in the manufacture of compound girders consisting of several separate. parts. In such a case a hollow" metal girder is obtained, in which the steps ,by no means necessary, I] have found it advantageous to slightly bend inwards also the broad faces of the channels.

In the drawings affixed to this specification and forming part thereof three modifications of a girder embodying my invention are illustrated by way of example.

In the drawings Figs. 1, 3 and 6 are cross sections on. the lines 1-1, 3-3 and 6-6,.

' respectively in'Figs. 2, 4.- and 5, while Figs. 2, 4 and 5 are perspective views of the three modifications.

- and 4 all four'faces f, g, with continuous steps tending all over the lengt circular openings 0 and d being provided Referring to Figs. 1 and 2 of the draw- -ings, the seamless tube has at first been transformed into a hollow beam of trapezoidal cross section whose narrow faces a and b are plane, while the broad -faces 15 0 and 01 present inward ste s0 and d exof the beam,

the edges h, i of the triangular openings h and i are bent inwards.

In the composite girder disclosed in Figs. 5 and 6 each of the two connecting strips. t consisting of thin steel, plate is provided with alternating circular holes u and transverse indentures 'v. The bordered edges w of the holes as well as the grooves extend in-- wards. The top and bottom flanges consist each of a channelv w of light metal whose flanges are riveted to the connecting strips t. The rivets (not shown) have their heads sunk in the flanges of the channels so so as not to project beyond the outer faces thereof. Flat longitudinal grooves .20 serve for stiffening the channel faces and further also facilitate the sewing together of a fabric envelope vwhich might be required to be provided for the beam.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for ob.- vious modifications will occur to a person skilled in the art.

I claim 1. A hollow metal beam of quadrangular section, comprising in combination, fou'r thin walled webs and depressions and beaded openings in two webs.

2. A hollow metal beam of quadrangular section, comprising in combination, four thin walled webs and depressions and openings in two webs, the edge portions of said openings being depressed inwards.

3. A hollow metal beam of quadrangular section, comprising in combination, two channels facing one another, flat strips fixed to the lateral webs of and connecting said channels and beaded openings and transverse depressions formed in said strips.

In testimony whereof I aflix my signature.

CLAUDE Bosnian. 

